1. Field of the Invention
The present invention relates to a sheet feeding device, and more particularly to a sheet feeding device having a nip mechanism in a roller pair for feeding a sheet and a transversely shifting mechanism for transversely shifting a sheet.
2. Description of the Related Art
Generally, a roller pair of feeding a sheet comprises a fixed roller and a nip roller movable toward and away from the fixed roller.
Some sheet feeding devices comprise two roller pairs that are successively operated into open and closed positions. The nip rollers of the respective roller pairs are individually associated with respective displacing mechanisms for displacing the nip rollers. Because of these displacing mechanisms, the sheet feeding device are poor in durability and high in cost. The individual displacing mechanisms take up a large installation space, resulting in a difficulty in effectively utilizing an available space.
Heretofore, the sheet feeding devices have a positioning mechanism for transversely positioning a sheet. The positioning mechanism comprises a positioning plate extending along the direction in which to feed the sheet and a presser for pressing the sheet against the positioning plate. The positioning plate positions one side edge of the sheet. If the positioning mechanism is used to position a sheet in an apparatus for reading or recording images, then an image can accurately be read from or recorded on the sheet at a desired position thereon.
The positioning mechanism positions the sheet with respect to one of its side edges. Therefore, if sheets of different sizes are used in the image reading or recording apparatus, then a sheet is fed in a different position depending on the size of the sheet. At this time, the pressure applied to the rollers for feeding the sheet is brought out of transverse balance, with the result that the sheet may not be kept in an accurate position in its transverse direction.
It is therefore an object of the present invention to provide a sheet feeding device which is highly durable, can be manufactured inexpensively, and has a nip mechanism that allows an available space to be utilized effectively.
Another object of the present invention is to provide a sheet feeding device which is simple in structure and has a transversely shifting mechanism capable of positioning a sheet accurately in the transverse direction thereof.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.